It was pretty the first mission of the Avengers team since defeating Thanos; things had been tense after the Sokovia Accords were overturned after a few months and the UN pardoned Captain America and his 'rogues' as Tony unaffectionately called them (but the media and the public called the group Avengers). Thaddeus Ross was arrested and sentenced after his dirty laundry was revealed to the public and the incident that caused the downfall of the Accords.
Tony Stark was still salty after having to work with them again but he had little choice; Steve was the leader of the Avengers as officially made by the UN and the Avengers had no objection to the idea that Steve was a better leader than Tony was. He was moaning about them mooching off his resources and the place he provided for them when they were doing nothing of the sort; in fact he had conveniently forgotten that he had signed over the facility that was now the Avengers Facility and everything in them over to the Avengers when he had temporarily retired after Ultron.
Will they now had another mission and it involved using time travel using the Pym Particles which was achieved by the tense teamwork between Scott Land, Hank Pym, Bruce Banner and Tony himself. Tony was ignoring the thanks that was given to him by Steve and the others and continued to moan that he was doing most of the work for the team.
They had to split into teams and Steve, Tony and Thor were in one and they had to go back to all the way back to World War II so they could infiltrate a SSR base in order to find a document that would lead to the long lost holding base of a dangerous weapon that was found and locked up in an undiscovered location. They had went back to World War II, just as the US joined the war since in a week a HYDRA spy attempted to steal it but it caused a gun fight that resulted in a fire that claimed the document and several others.
At first they were discovering where to go in an old diner that Steve said that he and Bucky used to go to. They had taken old money to use and Steve was disguised in a baseball cap and sunglasses so no one could recognise him. They sat down with Tony making comments about Steve's disguise when they spotted a table where Bucky (Tony made bitter comments towards him) and young Steve with Thor refusing to believe that it was Steve at first. "You could have used some good food there Capsicle..." Tony couldn't help but comment to raised eyebrows from Steve and Thor.
Then they heard someone yelling and saw it was a huge bald headed man making sexist comments and how the system didn't want him. "Harlan Krueger, an old bully. At this time he had gotten dishonourably discharged from the army for crimes against humanity and getting thrown out of the police force because he treated them like film serial adventures with him as the main hero." Steve explained and they saw the younger Steve shout to Harlan to show some respect after Krueger was harassing woman with sexist comments as well as trying to bully the brother of the police chief who had him thrown out.
Krueger shouted asking if little Steve wanted a beat up but Steve stood up and was defiant, "So you were always a mindless idiot who just charged into fights with no regard to consequences..." Tony muttered only to get glared harshly at by Steve and Thor. Thor went up and got in front of young Steve to stare down Krueger with Thor telling the man that he doesn't like the attitude of this bully either.
This caused Harlan to angrily go and punch Thor in the face as hard as he could; Thor didn't even flinch as Krueger was shouting about his broken hand and was then angrily thrown out by the diner's owner. Since the trio were done with their food they headed to the exit as well.
Krueger being an idiot and not wanting to let his broken hand go went to fight Thor again, all it resulted was him being thrown headfirst into a trash can with his legs moving in the air before fell down on its side. "So young Capsicle; someone who only became a somebody because of something that came out of a bottle..." Tony remarked and Thor had enough of his attitude and was about to tell him off when they saw the young Steve Rogers and Bucky Barnes come up to them.
"Thanks for the help there again Harlan, also you forgot your weird hammer by your seat." Young Steve told Thor and the trio looked and had their eyes widened when they saw that while young Steve was struggling with both hands, he was indeed holding Mjolnir.
Tony and Thor were staring at Steve with him trying to be silent and humble; Thor was in glee looked like he wanted to burst out shouting that he knew it. "Weird hammer you have there, I couldn't movie it and yet Steve here was able to. Looks like his time at the gym is finally paying off." Bucky remarked and Thor thanked young Steve before the trio left to go to that SSR base.
I made this with Tony's behaviour in this a kind of a parody of those Anti Cap and Tony prop stories. People who like those are free to like them but we are also free to write our own fics. I don't see how some people think that Tony is an angel who does help everyone instead of being a sarcastic jerk who talks down people more often than not. Plus I hate the depictions these type of fics give to Steve the best hero in the MCU, his claim of Tony being the greatest defender in Infinity War is nothing to me more than just him being modest.